Process of making azo dyes.



UNITED STATES Patented October 13, 1903.

PATENT OFFICE.

-FRANZ SOHOLL, OF I-lQOHST-ON-THE-MAIN, GERMANY, ASSIGNORTO FARBWERKE, VORM. MEISTER, LUOIUS & BRUNING, OF HOOHST- ON-THE-MAIN, GERMANY, A CORPORATION GERMANY,

PROCESS OF MAKING AZO D YES.

SPECIFICATION formingpart of Letters Patent No. 741,552, dated October 13, 1903.

Application filed February 4, 1903. Serial No. 141,850. (No specimens.)

T0 aZZ whom it mciy concern} Be it known that I, FRANZ SOHOLL, Ph; D.,

a citizen of the Empire of Germany, residing.

naphthalene-a-sulfonic acid with nitrous acid.

By the present invention some of these dyestuffs may be obtained in a direct but hitherto-unknown manner by combining the 1.8- azimidonaphthalene-at-sulfonic acid with the diazo compound in. the presence of a large excess of alkali. Hitherto the azimidonaphthalene sulfonic acid has been considered'to be a body incapable of reaction, (German Patent No. 70,019,) and indeed it has heretofore not been used for the manufacture of azo dyestuffs.

Among the diazo compounds suitable for use in this invention are those of picramic acid of 6-nitro-2-amidophenol--sulfonic acid and 4-nitro-2-amidophenol, the manufacture of dyestufis being illustrated, for instance, as follows: 25.6 kilos of 6-nitro-2-amidophenol- 4-su1fonate of sodium are diazotized with seven kilos of sodium nitrite and thirty kilos of hydrochloric acid of 20 Baum specific gravity. The yellow diazo solution is run into a solution of twenty-six kilos of 1.8-azior 15.4 kilos of nitroamidophenol are used.

The dyestuffs separate then mostly as crys tals without addition of common salt.

The dyestuffs thus obtained are identical with the corresponding combinations obtained by French Patent No. 316,866. They coincide as regards properties and advantages.

Having now described my invention, What I claim is- The herein-described process for the manufacture of azo dyestuffs, which consists in causing the diazo compounds of orthoamidophenol derivatives to act on 1. 8-azirnidonaphthalenel-sulfonic acid in an alkaline solution, substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed my name in presence of two subscribing witnesses.

FRANZ SOHOLL.

Witnesses:

ALFRED BRISBOIS, JoHANN HARTENSTEIN. 

